User interface system based on pointing device

ABSTRACT

The user interaction system comprises a portable pointing device ( 101 ) connected to a camera ( 102 ) and sending pictures to a digital signal processor ( 120 ), capable of recognizing an object ( 130 ) and a command given by the user ( 100 ) by moving the pointing device ( 101 ) in a specific way, and controlling an electrical apparatus ( 110 ) on the basis of this recognition.

This application is a continuation of U.S. patent application Ser. No.12/482,864, filed Jun. 11, 2009, now U.S. Pat. No. 8,537,231, which is adivisional of U.S. patent application Ser. No. 10/535,464, filed May 17,2005, now U.S. Pat. No. 7,940,986, which is a National Stage Applicationof PCT/IB2003/004830, filed Oct. 28, 2003, and which claims the benefitof European Patent Application No. 02079816.1, filed Nov. 20, 2002. Theentire contents of each of these applications are incorporated herein byreference.

The invention relates to a user interaction system, comprising:

-   -   an electrical apparatus;    -   a portable pointing device operable by a user for pointing to a        region in space; a camera taking a picture; and    -   a digital signal processor, capable of receiving and processing        the picture, and capable of transmitting user interface        information derived from the picture to the electrical        apparatus.

The invention also relates to a pointing device for use in a userinteraction system.

The invention also relates to an electrical apparatus for use in theabove mentioned user interaction system.

Such a system is known from US-A-2001/0030668. This document describes auniversal remote control system in which a user marks a location on adisplay with a pointing device displaying a recognizable characteristic,e.g. a laser pointer emitting a red spot, and a camera takes a pictureof the display and calculates to which location the user has pointed. Anelectrical apparatus, e.g. a computer or a television, then performs anaction corresponding to the marking by the user. E.g. if an icon on thedisplay is marked by flashing the laser pointer twice, a correspondingcomputer program is started.

It is a disadvantage of the known system that the system is tailored fora particular display. E.g. the display may be a projection from an LCDbased front projector on a screen, to which projector a laptop isconnected. The camera in the known system has such a position andviewing angle that it is capable of imaging the screen. Next, the DSP istrained to discriminate an area in pictures from the camera, whichcorresponds to the location of the screen. In the prior art this can bedone in a simple way. First a picture of the screen is captured bothwith and without illumination with a picture from the projector. Bycomparing the difference of those two pictures, the area of the displayin space as viewed by the camera is obtained. Second a perspectivetransformation is derived which determines the relation between alocation pointed to on the display and a location in the picture forprojection, in the frame buffer of the laptop. The known document alsodescribes pointing to a virtual display, e.g. a wall, by first manuallyselecting the corners of the virtual display. However the system isalways calibrated for one display and in case a user wants to interactwith another display, he has to set up the system again, or use a secondsystem.

It is a first object of the invention to provide a user interactionsystem of the kind described in the opening paragraph in which it isrelatively easy to interact with a number of available electricalapparatuses, more particularly displays.

It is a second object of the invention to provide a pointing device ofthe kind described in the opening paragraph which makes interaction witha number of available electrical apparatuses relatively easy.

It is a third object of the invention to provide electrical apparatusfor use in the above mentioned user interaction system.

The first object is realized in that the camera is connected to thepointing device so that in operation it images the region pointed to. Afixed camera only images a certain region of space. It is possible thatin the known user interaction system, the user's pointing device, or theobject pointed to are not even in the field of view of the fixed camera.It is a major advantage of a pointing device with an attached camera,e.g. on the front end of the pointing device closest to the regionpointed to, that the camera is always imaging the region pointed tosubstantially optimally. The object pointed to is in general theelectrical apparatus to which the user interface information, e.g.apparatus control data, is sent, but can be any object present in theroom in which the user resides, as long as it can be recognized by theDSP. The apparatus to be controlled is then identified e.g. by pointingto it previously.

In an embodiment according to claim 2 the user interface informationcomprises apparatus control data for controlling operation of theelectrical apparatus. There can be many apparatuses present in a livingroom which e.g. produce sound. Each of these devices has a control forincreasing or decreasing the sound volume. By pointing the camera of thepointing device towards a particular apparatus and performing a “volumeup” command, e.g. by pressing a button on the pointing device or makinga specific movement with the pointing device, the sound volume of thedevice pointed to will increase. Using a known universal remote controlcan have as a disadvantage e.g. that an apparatus responds which was notintended by the user, because it uses the same remote control code.

It is advantageous if as in claim 3 the digital signal processorcomprises an object characterizing means for characterizing an object orpart of the object present in the picture of the region imaged by thecamera, by providing first object characterizing features to a comprisedobject identification means for identifying the object, and which objectidentification means is capable of outputting object identification datafrom which the user interface information is constructed.

In case different electrical apparatuses are to be controlled, they allhave to be recognized automatically. The DSP can be e.g. a genericprocessor running algorithms for characterizing the apparatus, or it canbe an asic. Typically the object characterizing means will performimage-processing algorithms on a picture of the apparatus. E.g. therelative dimensions of the apparatus can be calculated and the numberand positions of buttons on the apparatus can be analyzed. The objectidentification means associate with these resulting first objectcharacterizing features a specific apparatus, e.g. from information inan apparatus table. Other information about the apparatus, e.g. “firsttelevision produced by company X with serial number Y” may be present,like the apparatus control data that the apparatus understands.

It is also advantageous if as in claim 4 the digital signal processorcomprises:

-   -   motion trajectory estimation means for estimating a motion        trajectory of the pointing device and outputting a first motion        characterizing signature, a signature being a mathematical        abstraction of the motion trajectory; and    -   signature identification means for identifying the first motion        characterizing signature and outputting command identification        data, which represents a user interaction command, corresponding        with the first motion characterizing signature, from which        command identification data the user interface information is        constructed.

To avoid the need of a large number of buttons on the pointing devicefor all the different commands that can be sent to all the differentapparatuses, and to make the user interaction system more user friendly,it is advantageous if at least some of the apparatus control data isgenerated on the basis of movements of the pointing device by the user,which pointing device is typically in his hand. The signature of anupwards movement could mean “volume up”, but in contrast with a standardremote control, the amount of volume change can according to theinvention depend on the brusqueness of the motion. If the user moves hisarm up slowly, the volume should e.g. change only slightly, and incontrast if he moves his arm up fast, the volume should go up a lot.Determination of the motion of the pointing device can be done on thebasis of motion sensing means, e.g. a mass on a deformation sensor, agyroscope, differential GPS, etc. However since a camera is alreadypresent, the motion can also be determined by imaging successivepictures and applying a motion estimation algorithm. Since global motionestimation is simpler than precise motion estimation of multipleobjects, the camera can be a simple CMOS based camera or even atwo-dimensional array of a small number of light sensitive elements.

It is also advantageous if as in claim 5 the digital signal processorcomprises identification improvement means, which are capable of furtherimproving a probability that the object represented as objectidentification data, and user interaction command represented as commandidentification data, are more reliably identified based on predeterminedrules, yielding more reliable user interface information. Sinceidentification of the object and motion signature need not always beperfect, given the variability of conditions in a room, identificationimprovement means can be incorporated which e.g. apply an artificialintelligence set of rules on the identified object identification dataand command identification data, possibly also taking into account thecharacterizing features first object characterizing features and firstmotion characterizing signature. E.g., a rule for determining theapparatus pointed to can take into account the room in which thepointing device is present, or the time of the day. E.g. the first thingwhat a user may typically do if he comes home and picks up the pointingdevice is to switch on the lights. His intention can be verified by theDSP on the basis of a picture of these lights.

It is further advantageous if as in claim 6 the predetermined rulescomprise probabilistic calculation of the likelihood of an {objectidentification data, command identification data}—pair, taking intoaccount at least one of the following a priori known information units{room in which the pointing device resides, previous command issued byuser, statistical frequency that a user issues a particular command andtime of the day}. E.g. the likeliness of a command can be calculatedbased upon a statistical profile of which commands a user usually uses,and based upon previously issued commands. Also, the likelihood of anapparatus can be updated based on the room in which the pointing deviceis present. On Friday at eight o'clock the user might want to watch hisfavorite television program.

It is also advantageous if as in claim 7 the digital signal processorcomprises object association means for providing to the objectidentification means object association data comprising at least one ofthe data entities being: associated object characterizing features andobject related data—,

-   -   the object association data being derivable from object template        data in object memory originating from at least one of the        methods:    -   the object template data is obtained from object training means        performing a predetermined calculation on second object        characterizing features outputted by object characterizing        means; and    -   the object template data is derived from inputted object data.

The user interaction system is much more versatile if, instead of beingpreconstructed by the manufacturer for controlling a fixed number ofapparatuses, the user can adapt it to his changing environment. E.g. ifhe buys a new apparatus, he would like this apparatus to be controllableby means of the same system. Also if he buys a calendar, hangs it on thewall, and points to it with his pointing device, he would like an actionto occur, e.g. starting up a calendar tool on his p.c. For this objectassociation means are required. The user images a new apparatus, e.g.under a few different angles. A number of image processing algorithmsrunning on the object characterizing means extract features for thisobject which are stored as an object template, possibly after firstcalculating invariant apparatus specific features. He then selects witha selection user interface which apparatus corresponds to this objecttemplate. This is a so-called training phase of the system. When laterthe system is used in a so called command phase, for sending apparatuscontrol data to an identified apparatus, the object identification bythe object identification means can be aided by means of the data storedin the object association means. E.g. on the basis of the objecttemplate data a number of associated object characterizing features,corresponding to what the object characterizing means output as firstobject characterizing features, can be sent to the object identificationmeans, which then performs a comparison, selecting the correctidentified apparatus. These features can also be preloaded in the objectidentification means. The object association means can also send objectrelated data to the object identification means, comprising at least anidentifier of the apparatus, and possibly further data such as supportedcommands. In an alternative realization, the object association meanscould also perform the object identification itself, in which case onlyobject related data is sent to the object identification means. To avoidthat the user has to input a lot of information through the selectionuser interface, object related data can also be inputted through anobject data input, e.g. directly from an apparatus to be identified andcontrolled. Via this input, characteristic object template data can alsobe inputted, e.g. the manufacturer of an apparatus might provide apicture taken under well-controlled imaging conditions.

It is also advantageous if as in claim 8 the digital signal processorcomprises signature association means for providing to the signatureidentification means signature association data—comprising at least oneof the data entities being: associated signature features and commandrelated data—,

-   -   the signature association data being derivable from signature        template data in signature memory originating from at least one        of the methods:    -   the signature template data is obtained from signature training        means performing a predetermined calculation on a second motion        characterizing signature outputted by the motion trajectory        estimating means; and    -   the command template data is derived from inputted command data.

According to a similar rationale, signature association means can becomprised to enable the training of new motion trajectories applied tothe pointing device by the user and characterized as signatures. Inthese realizations command data is inputted e.g. by an apparatus whichprovides a menu of its supported commands.

It is also advantageous if as in claim 9 the first motion characterizingsignature is derived on the basis of successive pictures imaged by thecamera at respective instances of time. Since a camera is attached tothe pointing device, imaging its every move, and global motion can beestimated by a simple motion estimation algorithm, successively imagedpictures can be used for deriving the intended user interface command.

The second object is realized in that the pointing device according toclaim 10 comprises a camera and is capable of sending a picture to aDSP. As already described above the user interaction system becomes moreversatile with such a pointing device.

An embodiment of the pointing device is characterized in claim 11 inthat it is capable of sending a picture to the digital signal processor,which is capable of sending user interface information to an electricalapparatus based on the picture

In an embodiment according to claim 12, the DSP is comprised in thepointing device. The pointing device can then also operate separate fromthe user interaction system. E.g. the pointing device can be taken to asupermarket, process imaged pictures and store the corresponding firstobject characterizing features. Control actions by home apparatuses canthen be performed at a later time.

It is advantageous if as in claim 13 the pointing device comprisesmotion sensing means for sensing a motion trajectory of the pointingdevice. Irrespective of whether the device is used for recognizingobjects, it can be used to send apparatus control data corresponding tospecific movements by the user. The intended apparatus in such anapplication of the pointing device could e.g. be fixed or indicated witha button.

It is advantageous if as in claim 14 the pointing device comprises acharacteristic projector for optically projecting a characteristicpattern towards a region pointed to. It is advantageous if the user getsa feedback of which apparatus or part of an apparatus he is pointing to.Otherwise, if he is not aiming correctly, he might e.g. virtually pushthe wrong button of the apparatus. One form of feedback could be a smallpicture on a display of the pointing device which shows the center ofthe region imaged by the camera. An apparatus or button on an apparatusin the middle of the display is the one intended. Another form offeedback comprises projection of a characteristic pattern, e.g. a whitecross, or a laser dot, which illuminates the intended part of anapparatus. More complex patterns such as a two-dimensional grid of linescan aid the DSP in identifying the geometry of the imaged apparatus.

It is advantageous if as in claim 15 the pointing device comprises aprogrammable user interface code generator and a wireless transmitterfor transmitting the code to the electrical apparatus. Instead of theDSP sending apparatus control data to the apparatus, e.g. by means of awireless home network based on bluetooth, the pointing device itself maydirectly send the appropriate remote control command, e.g. by means ofinfrared radiation. The advantage compared to a classical universalremote control is that the DSP automatically identifies the apparatus,from a camera picture, and generates the correct code.

It is advantageous if as in claim 16 feedback means are present forfeedback of user interface information. E.g. a display is useful.Another feedback can provide some kind of force feedback, e.g. by meansof a mass which is moved. This can e.g. simulate tipping against thescreen of a TV.

The third object is realized in that interface means are comprised whichallow the apparatus to send information about supported commands to apointing device as claimed in claim 1, based on an “identify supportedcommands” call of the pointing device to the apparatus. The DSP or partof the functionality of the DSP might also be comprised in theapparatus. The apparatus might also transmit object characterizingfeatures and so on.

The invention will be apparent from and elucidated with reference to thefollowing description and the accompanying drawing, showingschematically examples of components of the user interaction system andpointing device according to the invention. In this drawing:

FIG. 1 schematically shows a room in which a user interaction systemaccording to the invention is present;

FIG. 2 schematically shows a digital signal processor according to theinvention;

FIG. 3 schematically shows a pointing device according to the invention;and

FIG. 4A shows an example of a motion trajectory and correspondingsignature;

FIG. 4B shows another example of a motion trajectory and correspondingsignature.

In FIG. 1 a room is shown containing various electrical apparatuseswhich can receive user interface information I, e.g. electricalapparatus 110 being a plasma display, but also a personal video recorderor a telephone or a washing machine can be present, with which a user100 can interact. The room also contains various objects, beingelectrical apparatuses or just any physical object like e.g. a window,or object 130 being an audio apparatus, vase 170 and electricalapparatus 110, that can be pointed to by means of a pointing device 101.

According to the invention, the pointing device 101 contains a camera102, and can send pictures of regions of a room or objects in thoseregions to a digital signal processor (DSP) 120, which can identify theregions or objects on the basis of one or more pictures imaged by thecamera 102. The camera is connected to the pointing device 101 in such away, that it images well the region pointed to. E.g. it can typicallyreside at the far end of the pointing device 101, but it could also bemounted on the side under an angle. The user 100 has the freedom topoint to whatever object he wants, and in such a way a veryuser-friendly and powerful user interaction system can be realized.

The DSP 120 can be e.g. a home computer controlling apparatuses in ahome network, or it can be incorporated in the pointing device 101. Thecamera 102 can be a CCD camera or CMOS camera. The connection betweenthe camera 102 and the DSP 120 can be wireless if the two are separate.The pointing device 101 can already perform part of the algorithms to beperformed by the DSP 120 for identification of an object, so that e.g.only a small set of features need to be sent to the external DSP 120 forfurther processing. In fact the functionally shown DSP 200 can bedistributed in a number of parts in the pointing device 101, room,different apparatuses and so on.

The DSP 120 is designed to send user interface information I, e.g.apparatus control data ac, to an identified apparatus. E.g. user 100 canpoint the pointing device 101 to light 160 and push an on-button on thepointing device 101, which results in the DSP 120 sending an on-commandto the identified light 160. The object identified needs not be theapparatus to be controlled itself. E.g. pointing at vase 170 may start aparticular program on a p.c., the output of which is shown on thedisplay apparatus 110. Parts of an object may be pointed to, e.g.pointing at a volume button 134 of object 130 increases or decreases thevolume of this audio apparatus, in dependence on an additional actionsuch as the pushing of a button or a movement of the pointing device101. Pointing to the channel selection display 132 and making a sidewardmovement may change the channel. The DSP 120 may also recognize thestatus of a part of an object, e.g. that cassette loader 136 is leftopen, and issue a “close” command. Other specific situations can also bedetected or monitored. User 100 may also point to a piece of furniture140 or a part 142 thereof. If the piece of furniture 140 is a cupboarddifferent actions can result from pointing to different drawers. If thepiece of furniture 140 is an intelligent refrigerator, pointing to itcan result in the user defined action of ordering beer over theInternet. Apart from apparatus control data ac, other user interfaceinformation I can be sent, e.g. picture data pd. E.g. first electronicpainting 150 and second electronic painting 152 display a variablepicture. They can be realized with electrophoretic electronic inkdisplays. User 100 can capture the picture displayed on the firstelectronic painting, or even a picture on a calendar hanging on thewall, and transfer it as picture data pd to the second electronicpainting 152, possibly after some image processing such as e.g.perspective correction.

FIG. 2 schematically shows functional components in a digital signalprocessor 200—an embodiment of 120 in FIG. 1. Not all componentsdescribed are necessarily present in a particular embodiment of the userinteraction system. The DSP 200 can be realized as a generic processor,an asic, or separate components on a circuit board. The DSP 200 mayreceive camera input c and sensor input s, e.g. from motion sensingmeans 304. The DSP 200 may comprise an object characterizing unit 202for characterizing a picture of an object 130 or part of the object 130as imaged by the camera 102. The object characterizing unit 202 iscapable of providing first object characterizing features f1 to anobject identification unit 204. The first object characterizing featuresf1 may be of different kinds depending on the image processingalgorithms embodied in the object identification unit 204. Typically theobject is first isolated from the remaining parts of the imaged picture.This can be done e.g. on the basis of edge and curve detection on thepicture. Another option is 3D analysis of the imaged region, e.g. with aprojected grid or a second camera. Part of an object may be detected onthe basis of correlation techniques, and then the rest of the object canthen be verified.

Second the first object characterizing features f1 are calculated. E.g.a contour of the object and its composing parts can be characterized bymeans of a curvature versus angle characteristic. Or the ratiowidth/height may be calculated. Also, the isolated object region itself,or a transformation of it may be used, typically after first performinga perspective correction.

The object identification unit 204 then identifies the object on thebasis of the first object characterizing features f1 received from theobject characterizing unit 202. E.g. any known classification techniquein multidimensional feature space might be used. The output of theobject identification unit 204 is object identification data oi, whichcan be a simple number or a data structure containing additionalinformation about the identified object. The characterizing features andfurther data of a number of apparatuses might be e.g. stored a priori inan object characteristics memory 230 by the manufacturer of the pointingdevice containing the DSP 200, or might be preloaded from internet ifthe DSP 200 is a computer. Instead of identifying an object, the DSP mayalso identify a region of the room. E.g. pointing the pointing device101 towards the ceiling may issue the command “lights on”, whereaspointing to the floor switches the lights off. Or pointing to one of thecorners may invoke an associated command. The corners may be identifiedon the basis of objects present, e.g. on the left side a plant and onthe right side a cupboard.

The user interaction system is much more useful however if a user cantrain new objects, such as vase 170, himself. Therefore an objectassociation unit 212 might be comprised, which provides the objectidentification unit 204 with object association data oad. The objectassociation data oad might comprise characterizing features fa of anobject, similar to the first object characterizing features f1, based onan object template. The object template can be obtained by applying atraining phase. A new object is imaged by the camera 102 under a numberof conditions, e.g. different angles, lighting etc. The objectcharacterizing unit 202 generates second object characterizing featuresf2 for all the pictures. An object training unit 221 in the objectassociation unit 212 generates an object template corresponding to theobject which is stored in object memory 220. The template can e.g. bethe cluster of second object characterizing features f2 of all thepictures, or average features, or some invariant feature calculated onthe basis of the variable second object characterizing features f2. Theobject template might also be derived by the object training unit 221 onthe basis of characterizing features coming in from the outside asobject data od. This object data might originate from an apparatus whichinputs e.g. pictures of it taken from different angles by amanufacturer. The object data od and object association data oad mightalso comprise object related data id, i.e. all kinds of informationconcerning an apparatus, like e.g. supported commands.

To facilitate object recognition, certain objects like e.g. apparatus110 may display a characteristic pattern 116, e.g. they may flash a redcross a predetermined number of times with different on/off intervals,in response to an “object identify” call of the pointing device. Theapparatus 110 might also comprise an interface unit 190, which makes itmore useful in a user interaction system according to the invention.E.g. an apparatus like an internet radio can have a “service discovery”function which communicates to the pointing device 101 which commands itsupports. It might even transmit infrared remote control sequencescorresponding with these commands, and so on. This facilitates thetraining of the DSP 120, 200 by the user 100. E.g. in response to thecommunication, the commands can appear as a menu of predefined icons ona display 316 of the pointing device 101. The interface unit 190 canalso be realized separately. E.g. a washing machine might not have anintricate remote control facility. A plug-on box can be provided whichreceives standard commands from the DSP 200 and interfaces in a simpleway with the apparatus, e.g. starting it.

The DSP 200 might also comprise components for analyzing gestures madewith the pointing device 101 by the user 100. For this, the motiontrajectory 400 in FIG. 4 of the pointing device 101 is used, which iscalculated e.g. on the basis of pictures from the camera 102. FIG. 4 ashows an upward motion trajectory 400 in a three-dimensional coordinatesystem 404. It is summarized by signature 402 being a mathematicalrepresentation of that upward motion trajectory. The signature 402 canbe linked, e.g. by means of a command table, with command identificationdata ci, e.g. in this case the user 100 might reserve this motion for a“volume up” command. A circular motion trajectory 410 and circularsignature 412 might mean to one user “rewind”, whereas another user hastrained the DSP 200 to relate this circular signature 412 with a “deviceon” command. The user can e.g. roughly orient his pointing device 101towards light 160 and make the “device on” motion, on the basis of whichthe DSP 200 switches the light 160 on. Alternatively the user 100 canalso make the “device on” motion somewhere in the air and then point tolight 160, or a television or whatever object he wants to be switchedon. The signatures 402, 412 can be parameterized in any way and matchedby any known curve fitting technique. E.g. the signature 402 can becoded as a number of connected line segments of specific length andintersegment angle.

A motion trajectory estimation unit 206 calculates a motion trajectory400, on the basis of motion sensing means 304, or successive picturesfrom the camera 102. E.g. optical flow or block based motion estimationtechniques can be applied on two successive pictures to obtain a part401 of motion trajectory 400. The divergence of the motion vector fieldcan be used to estimate motion towards on object, i.e. typically alongan axis of the pointing device 101. On the basis of motion trajectory400. a signature generation unit 209 outputs a first motioncharacterizing signature s1. A signature identification unit 208identifies the first motion characterizing signature s1 and link it withcommand identification data ci, being e.g. a numerical representation ofa user interaction command intended by the user 100. The first motioncharacterizing signature s1 can be compared with signaturecharacteristics for different stored signatures in a signaturecharacteristics memory 232. E.g. if a roughly circular or even anyreturning movement is made, a stored circular signature template willyield a better match than a linear signature template. Geometrical andstructural curve matching techniques can be applied in the similaritycalculation.

Just like it is advantageous to have a DSP 200 which is able to learn toidentify new objects, it is advantageous if the DSP 200 can identify newmovements preferred by the user 100. Therefore the signature associationunit 214 might be comprised for providing signature association data SADto the signature identification unit 208. The signature association dataSAD may comprise associated signature features sa, e.g. a mathematicalrepresentation of the circular signature 412, and/or command relateddata cid, e.g. received from an apparatus sending its supported commandsas command data cd to the DSP 200. Signature templates in a signaturememory 222 can be obtained from a signature training unit 223 on thebasis of a first motion characterizing signature s2 from the motiontrajectory estimation unit 206 or from command data cd.

Since the environment of the user is very variable, e.g. the lightingchanges during the day, the identification of the object 130 or acommand, i.e. a signature 402, might sometimes be incorrect. Thereforethe DSP 200 might comprise an identification improvement unit 210. Theintended command is e.g. dependent on the object 130 pointed to, ormight be dependent on the command given previously, and so on. An objectis identified incorrectly if it is not present in the room the pointingdevice is residing in. Therefore room recognizing means 185 may bepresent, e.g. flashing LEDs. The user 100 can scan the room recognizingmeans 185 with the pointing device 101 when he enters the room. Apartfrom the camera 102, a photodiode might be comprised in the pointingdevice 101 for detecting the room recognizing means 185. Roomlocalization beacons 180, 181, 182 may also be present, so that the DSP200 can recognize to which part of the room the pointing device 101 ispointing. The beacons could be light emitting in case the camera 102 isto recognize them, but they could also e.g. emit electromagneticradiation. Objects present in the room can also aid in the recognitionof an object. E.g. if vase 170 is next to object 130, its recognitioncan aid in the recognition of object 130. Even analysis of the pasttrajectory of the pointing device can be used. If the pointing devicewas previously pointing to object 130 and it has been moved to theright, it should be pointing to apparatus 110. Taking all thisinformation into account, the identification improvement unit 210 cancalculate e.g. Bayesian probabilities or use fuzzy logic to arrive at amore certain identification of the object 130 and the intended command.

The user interaction information I outputted by the DSP 200 typicallycomprises control apparatus data ac, being e.g. a structure comprisingthe object identification data oi and the command identification dataci, or a new identifier based on those, identifying an intended commandfor a particular apparatus 110. The user interaction information I mayalso comprise picture data pd.

FIG. 3, schematically shows a pointing device 300—an embodiment of 101in FIG. 1—according to the invention. Not all features shown need bepresent: a simple pointing device may only comprise a camera 302 ande.g. a display 316 for feedback. A number of buttons e.g. button 308might be present. This allows for giving certain commands only bepushing a button. Also similar movements of the pointing device 300 canbe used for two different commands, once with and once withoutsimultaneously pushing the button 308. A characteristic projector 320may be present, e.g. for projecting a laser spot towards the locationpointed to. The camera of the pointing device is capable of sending apicture to the external DSP 120, but it might also itself comprise theDSP 200. In this way the pointing device can also be used outdoors. Apointing device 103 not carried by the user 100 might also be used tomonitor an apparatus 110 or room. Apart from sensing the motion by meansof the camera, other motion sensing means 304 may also be comprised,e.g. a gyroscope or differential GPS. A programmable code generator 309and wireless transmitter 310 may also be present for sending a commanddirectly to an apparatus 110. Feedback means might be present forproviding the user with additional information. E.g. a light 312, asound production device 314, a force feedback means 306, and inparticular a display 316 might be comprised. The force feedback meanscan comprise a small moveable mass, which can simulate vibration or thetouching of an apparatus. The display can show e.g. the center of theregion pointed to, possibly superimposing a graphically generated crossin the center of the picture imaged. This can also be displayed on atelevision. Similarly the light 160 might be used to provide feedbackinstead of light 312. The feedback on the display 316 might show e.g.the motion trajectory 400 and how similar it was to previous motiontrajectories during the motion trajectory training phase, aiding theuser 100 to learn the DSP 200 to recognize a stable gesture. The display316 might also indicate what the DSP 200 sees by showing a picture aftera number of image processing steps, e.g. a picture containing detectededges, and comprising text naming the identified device.

User identification means 330 might also be present, e.g. a fingerprintsensor, or an input for a password or personal smart card. In this waythe DSP 200 can set itself to a mode of operation particular to the user100. The user might even give different commands depending on the roomhe is in. Speech recognition means 340 may also be comprised, tosupplement the commands given by movements of the pointing device 300.Games could be played by using the pointing device 101 as some kind ofinterface device to the real world.

The invention claimed is:
 1. A user interaction system, comprising: anelectrical apparatus; a portable pointing device operable by a user forpointing to a region in space; a camera taking a picture, which camerais physically attached to the pointing device so that in operation itimages the region pointed to without imaging the pointing device; adistributed digital signal processor, the digital signal processor beingcapable of receiving and processing the picture, and capable oftransmitting user interface information derived from the picture to theelectrical apparatus; at least one localization beacon that can emitelectromagnetic radiation for use by the digital signal processor inorder to recognize where the pointing device is pointing; wherein thedigital signal processor estimates a motion or a motion trajectory ofthe pointing device; and, wherein said digital signal processorrecognizes where the pointing device is pointing without imaging anyelectromagnetic radiation emitted from the pointing device itself. 2.The user interaction system as claimed in claim 1, wherein thetransmitted user interface information includes at least one featureselected from the group consisting of motion speed, and motion directionof the pointing device.
 3. The user interaction system as claimed inclaim 1, wherein the transmitted user interface information includes atleast one feature selected from the group consisting of motiontrajectory of the pointing device and a characteristic signature derivedfrom the motion trajectory of the pointing device.
 4. The userinteraction system as in claim 1, wherein the user interface informationcomprises apparatus control data for controlling operation of theelectrical apparatus.
 5. The user interaction system as in claim 1,wherein the motion or the motion trajectory of the pointing device isestimated on basis of motion sensing means.
 6. The user interactionsystem as in claim 1, wherein the motion or the motion trajectory of thepointing device is estimated on basis of successive pictures imaged bythe camera at respective instances of time.
 7. The user interactionsystem as in claim 1, wherein the digital signal processor isdistributed in a number of parts.
 8. The user interaction system as inclaim 7, wherein a first part of the digital signal processor isincluded within the pointing device and a second part of the digitalsignal processor is included within the electrical apparatus.
 9. Theuser interaction system as in claim 1, wherein the digital signalprocessor is arranged to analyze gestures made with the pointing devicebased on said motion trajectory.
 10. The user interaction system as inclaim 9, wherein the pointing device is arranged to control an operationof the electrical apparatus based on said analyzed gestures.
 11. Theuser interaction system as in claim 1, wherein the motion trajectory issummarized by a signature which is a mathematical representation of saidmotion trajectory.
 12. The user interaction system as in claim 11,wherein the signature is linked to a command for controlling theelectrical apparatus.
 13. The user interaction system as in claim 11,wherein the signature is matched by a curve fitting technique.
 14. Theuser interaction system as in claim 1, wherein the pointing devicefurther comprises feedback means for providing a user with feedback ofwhich part of the electrical apparatus the user is pointing to.
 15. Theuser interaction system as in claim 14, wherein said feedback means isselected from the group consisting of light, sound, and a display. 16.The user interaction system as in claim 14, wherein said feedback meansis force feedback means.
 17. An electrical apparatus for use in a userinteraction system as in claim 1, characterized in that interface meansare comprised which allow the electrical apparatus to send informationabout supported commands to a pointing device based on an “identifysupported commands” call of the pointing device to the electricalapparatus.
 18. A method of interacting between an electrical apparatusand a portable pointing device, the device being physically attached toa camera, the method comprising: pointing the pointing device to aregion in space; taking a picture with the camera, wherein the pictureis of the region pointed to, and wherein the picture does not containany image of the pointing device; receiving and processing the picture;receiving electromagnetic radiation from at least one localizationbeacon; recognizing where the pointing device is pointing by at least inpart on utilizing the received electromagnetic radiation; transmittinguser interface information derived from the picture to the electricalapparatus; wherein the processing step comprises estimating a motion ora motion trajectory of the pointing device; and, wherein the recognizingstep does not image utilize any electromagnetic radiation emitted fromthe pointing device itself.
 19. The method of claim 18 furthercomprising the step of utilizing a motion sensing means in estimatingthe motion or the motion trajectory of the pointing device.
 20. Themethod of claim 18 further comprising analyzing successive picturesimaged by the camera at respective instances of time in estimating themotion or the motion trajectory of the pointing device.
 21. The methodof claim 18 further comprising analyzing gestures made with the pointingdevice based on said motion trajectory.
 22. The method of claim 21further comprising controlling an operation of the electrical apparatusbased on said analyzed gestures.
 23. The method of claim 18 furthercomprising summarizing the motion trajectory by a signature which is amathematical representation of said motion trajectory.
 24. The method ofclaim 23 further comprising linking the signature to a command forcontrolling an operation of the electrical apparatus.
 25. The method asin claim 18, wherein the pointing device further includes the step of,providing feedback to a user with feedback of which part of theelectrical apparatus the user is pointing to.
 26. The method as in claim25, wherein said feedback is force feedback means.
 27. User interactionsystem, comprising: an electrical apparatus; a portable pointing deviceoperable by a user for pointing to a region in space; a camera taking apicture, which camera is physically attached to the pointing device sothat in operation it images the region pointed to without imaging thepointing device; a distributed digital signal processor, the digitalsignal processor being capable of receiving and processing the picture,and capable of transmitting user interface information derived from thepicture to the electrical apparatus; at least one localization beaconthat can emit electromagnetic radiation for use by the digital signalprocessor in order to recognize where the pointing device is pointing;wherein the digital signal processor estimates a motion or a motiontrajectory of the pointing device; and, wherein said digital signalprocessor recognizes where the pointing device is pointing withoututilizing any electromagnetic radiation emitted from the pointing deviceitself, except for transmitting user interface information to theelectrical apparatus.